Reactive dyestuff generally indicates that dye molecule contains a reactive functional group that can react with fiber. It can react to the hydroxyl group of cellulose fiber or the amide, imino and carboxylic acid group in animal and polyamide synthetic fibers. Thus, with the covalent bonding between the dyestuff and fiber, the purpose of dying is achieved.
Red (or yellowish red) reactive dyestuffs are already known from U.S. Pat. Nos. 5,075,428, 5,354,849, and 5,359,042.